This invention relates to a vehicle suspension system and particularly to a vehicle suspension system that incorporates a special wishbone stabilization assembly that cooperates with a torque beam to define parallelogram stabilization on both sides of the axle and incorporates a lift spring, all in a highly compact air spring suspension.
This suspension system is particularly suited for a pusher or trailing axle application. The suspension system is extremely compact with various components serving a plurality of functions. In brief, the suspension system includes a hanger assembly that depends downwardly from a side rail of the vehicle chassis. The hanger assembly provides a connection for a bushing assembly on which the end of a torque beam is mounted. The hanger assembly also provides a seat for supporting the bottom end of a lift spring with the top end being connected to the torque beam. The lift spring has a built-in bumper that limits downward travel of the axle. Also, a shockabsorber becomes fully extended to assist the lift spring in this limiting function.
A cross channel member is connected between the hanger assembly and a like hanger assembly on the opposite side of the vehicle. The cross channel assembly serves as a stabilizing connection between the hanger assemblies. The cross channel assembly also provides a point of installation for the forward central portion of a wishbone stabilizer assembly. The wishbone stabilizer assembly comprises a pair of diverging arms that are joined together at their forward ends where the assembly is connected to the cross channel assembly by a unique bushing and marsh spring assembly.
An axle seat assembly provides connections to the axle. It also provides connection points for the rearward ends of the torque beam and one of the diverging arms of the wishbone stabilizer assembly. The axle seat assembly further provides a connecting point for a shock absorber and through its connection to the axle, provides a connection for a bracket to which an end of a hydraulic cylinder is connected, the other end being connected to the tie rod.
The wishbone stabilizer assembly provides a lower component of a parallelogram, the upper component of which is defined by the torque beam and both components are pivotally connected between the hanger and cross channel assembly and the axle seat assembly. The wishbone stabilizer assembly also provides lateral stabilization and eliminates the need for a sway bar. Thus the wishbone stabilizer assembly provides a common link between the left and right side suspension systems and provides the lower parallelogram component for both sides in cooperating with their respective torque beams.
The special resilient bushing and marsh spring assembly that connects the wishbone stabilizer assembly to the cross channel assembly allows for conical movement of the wishbone stabilizer assembly. This complex connection accommodates the complex movements of the wishbone stabilizer assembly, such as occur when one side only of the vehicle moves vertically relative to the axle.
The diverging arms of the wishbone stabilizer assembly cooperate with the torque beams to provide lateral stabilization and eliminate the need for a sway bar or lateral guide. Because the two torque beams on opposite sides of the vehicle prevent the axle from moving longitudinally, and because the angular convergence of the arms of the wishbone stabilizer assembly would require longitudinal movement of the axle in the event of sway, the resulting combination eliminates sway of the axle.
The parallelogram maintains constant pitch or caster of the axle. Also, by preventing the axle seat from rotating about a transverse axis, the parallelogram maintains the attitude of the air spring, utilizing its full stroke.